The present invention is broadly concerned with a pellet implant system that administers a growth stimulating pharmaceutical pellet dosage in combination with a parasiticidal, antimicrobial, estrus suppressant and/or other supplemental pellet dosage subcutaneously in a single procedure in order to promote physiological growth which is synergistically augmented and promoted by control of parasites, microbes and/or estrus and the like.
More particularly, it is concerned with an implantation device having a pellet magazine containing pellets having a growth stimulating pharmaceutical in combination with a parasiticide, an antimicrobial agent and/or an estrus suppressant or other supplemental agent in a growth promoting combination as well as an injection needle and structure permitting injection of the pellets from the magazine through the needle for implantation under the skin of an animal. The pellets are formulated to simultaneously deliver doses of the various components that are released in the body of the animal according to a predetermined schedule.
Subcutaneous implantation of pharmaceutical compositions and medical devices has been widely adopted for therapeutic, health and growth enhancement purposes for livestock and companion animals, humans and even certain wild animals, such as those maintained in parks and zoos. Various growth promotants are employed to foster improved growth and enhanced body weight in livestock animal species such as cattle, swine, sheep, poultry and the like.
Broad spectrum endectocides, that is, pharmaceutical compositions which control both internal and external parasites, are now available to control the numerous members of the Arthropoda and Nematoda phyla, such as flies, mosquitoes, midges, keds, lice, maggots, mites, ticks, and their larvae, worms, wasps, and predaceous beetles and have been applied to animals in various ways. Antimicrobials have been employed for prophylactic as well as acute treatment of respiratory and other bacterial diseases. Estrus suppressors are used to maintain appetite and enhance growth, especially in cattle.
These compounds have been employed for various purposes to effect the health of animal populations, as well as production, performance and reproductive efficiency. Some of these compounds also relieve discomfort which may accompany pest infestation and infection. Other types of biologically active compounds, including vitamins, anti-inflammatory agents, vaccines and biocides are also commonly used to improve the health status of animal populations.
Some of these compositions are implantable in animals, such implantable compositions are often administered as solid compressed pellets which are injected by an implanter equipped with a hypodermic needle. In livestock implants are normally made in the ear or in other areas of the animal that are not for consumption and are discarded. The implanter needle is used to make a small self-sealing and noncoring implant-receiving puncture beneath the skin at a suitable location on the body of the animal. Small pellets of a bioactive composition are forced through the needle and left under the skin as the needle is removed.
The pellets are normally implanted in non-poultry livestock animals while the animal is confined in a squeeze chute. Using head restraint, an ear is grasped in one hand, and an implanter device having a large hypodermic needle is used to puncture the hide and subcutaneously inject a pellet dose into an implant-receiving puncture. Implantation must be performed carefully to ensure that the pellets are placed properly and that no portion of the pellet remains extending from the puncture outside the hide. The procedure must also be performed quickly, since the animals are not entirely cooperative and may shake their heads to free the held ear.
U.S. Pat. No. 5,522,797 and entitled Slide Action Veterinary Implanter, is directed to an implanter of the type described above and is hereby incorporated by reference. This patent discloses an implanter which employs a slide action mechanism to retract an impeller, store an impeller driving force in a spring in cooperation with a latch mechanism, reset a trigger, and advance a pellet magazine, all by a single trigger actuated reciprocation of the slide mechanism. Operation of the trigger also forces the pellets from the magazine through the needle and under the skin of the animal.
Efficient implanters, such as that taught in the above noted patent and other patents to similar implanters, permit rapid sequential injection of many animals in a single session and make implant technology particularly well-suited for administration of bioactive compositions, while the animals are confined for ear tagging, branding, veterinary procedures or the like. Even where only a single animal is to be treated, implantation offers a particularly safe method for administering certain compositions, so as to allow a user to avoid compounds that could be toxic if ingested by the animal, for example by licking residue left on the hide or fur, or on that of another animal following treatment by dipping, spraying or dusting.
Physiological growth and weight gain in particular are of primary importance in livestock animals raised for meat. Parasite control has long been a primary goal of animal husbandry. A number of effective endectocides and insect growth regulators are available for control of arthropod and nematode parasites, including the polyketide avermectins, the milbemycins and milbemycin oximes, fenbendazole, pyriproxyfen and lufenuron, diflubenzuron, methoprene, ethyl carbamate and fenoxycarbu. The most commonly used avermectins are ivermectin, doramectin, moxidectin, eprinomectrin and abamectin. U.S. patent application Ser. No. 09/163,646, now U.S. Pat. No. 6,645,192 for Pellet Implant System for Immediate and delayed Release of Antiparasitic Drug, which is incorporated herein by reference, discloses a system which delivers subcutaneously pellet implants of varying controlled release parasiticidal dosages to provide immediate as well as sustained release of the parasiticide for a period of up to several months without redosing.
Respiratory disease and its consequent growth impairment is a particular problem among crowded animals, such as is found in feedlots. Suitable antimicrobial compositions include tylosin tartrate, tylosin, oxytetracycline, tilmicosin phosphate, ceftiofur hydrochloride, ceftiofur sodium, and sulfadimethoxine. Prophylactic administration of these antibiotics permits usage of lower doses than those required to treat an infected animal.
Similarly, estrus-induced appetite inhibition in food animals diminishes weight gain. Effective growth promoting pharmaceutical compositions are available, including the progestins, estradiol and its derivatives, trenbolone acetate, testosterone and zeranol. Somatotropins and gonadotropins are also used for various purposes in livestock.
It has been noted in accordance with the present invention that administration of a growth stimulating composition in association with effective control of internal and external parasites results in a highly effective growth promoting composition and an augmentation of the physiological growth of the animal. In certain circumstances, the animals may even gain significantly more weight than is predicted from summation of the predicted effects of the individual compounds, as there is a synergistic effect associated with combining the various compositions and implanting them together. Accordingly, there is a need for a system which delivers subcutaneously pellet implants of both a growth stimulating pharmaceutical dosage in combination with a parasiticidal dosage, an antimicrobial dosage, an estrus suppressant dosage and/or other supplemental agents to provide control of parasites, microbial infection, estrus and maximize promotion of growth.